Stevens connected on scoring throws to Cameron Butler and Dalton Fackrell, and Izzy Matthews ran for a 5-yard touchdown as the Buffaloes built a 24-0 lead midway through the second quarter.
Dalyn Dawkins ran for 121 yards to lead Colorado State (4-2, 2-0 Mountain West). Matthews finished with 84 yards rushing.
Utah State’s DJ Nelson blocked a punt and returned the ball 20 yards into the end zone to make it 24-7 with six minutes left before halftime. Kent Myers threw a 22-yard touchdown pass to LaJuan Hunt for Utah State (3-3, 1-1) with 1:37 remaining.
Colorado State had 509 yards of total offense. Utah State finished with 212 yards, of which 69 yards came in the Aggies’ late scoring drive.